National Air Traffic Services (Nats) confirmed that two BMI British Midland planes came within one-and-a-half miles of each other.

The incident involved one plane flying from Heathrow airport to Brussels, and one flying to Heathrow from Paris.

Safety rules state that aircraft should be at least five miles apart.

Warnings received

The near miss is being blamed on a mistake by an air traffic controller at West Drayton.

There were a total of 148 people on board the two planes, when the incident occurred about 20 miles east of Gatwick airport on Tuesday.

It is understood that the pilots of both aircraft took action after receiving warnings from a controller at West Drayton and from their automatic collision avoidance systems.

The airline and Nats have both filed safety reports.

The Civil Aviation Authority will now investigate the incident.

MP's questions

The near-miss is the latest in a series of such incidents.

There were reports last Friday that a British Airways (BA) flight to Paris and a Swiss-bound plane had to alter their courses after flying too close over Brighton.

On 3 July, two BA flights had a near-miss 10 miles from Llandrindod Wells in Powys, Wales.

Local MP Roger Williams wrote to UK Transport Secretary Alistair Darling and the Civil Aviation Authority asking if the incident was linked to the newly-privatised National Air Traffic Control System.

Just two days earlier, two large jet aircraft collided over southern Germany.

At least 70 people died, most of them schoolchildren.

And in June, a passenger plane from Islay came close to colliding with a military aircraft as it was being guided into Glasgow airport by air traffic controllers.